A porous high-entropy rare earth monosilicate ceramic powder, a preparation method and application thereof

Abstract

The application discloses a kind of porous high-entropy rare earth monosilicate ceramic powder and preparation method and application thereof, it is related to high-entropy ceramic technical field, comprising the following steps: S1, tetraethyl orthosilicate is dissolved in anhydrous ethanol, fully stirred, as silicon source solution;S2, silicon source solution is added to rare earth nitrate solution, fully stirred, to obtain mixed solution;S3, sodium hydroxide solution is added to mixed solution as rare earth ion coprecipitation agent and tetraethyl orthosilicate condensation catalyst, it is sealed in reactor and reacted for 24-60h, precursor gel is obtained after separation and drying;S4, precursor gel is calcined at 1350-1400 ℃ for 2-4h and then quenched to room temperature, to obtain porous high-entropy rare earth monosilicate ceramic powder.The porous high-entropy rare earth monosilicate ceramic powder provided by the application has the characteristics of uniform element distribution, large component space, no impurity phase, low thermal conductivity, etc., as well as the advantages of simple equipment and controllable process, and is suitable for use in aero-engine hot end components, with wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of high-entropy ceramics technology, specifically to a porous high-entropy rare-earth monosilicate ceramic powder, its preparation method, and its application. Background Technology

[0002] A high thrust-to-weight ratio has always been a goal pursued by advanced aero-engines. However, as the thrust-to-weight ratio of engines continues to increase, turbine inlet temperatures are also constantly rising, making it difficult for existing high-temperature alloy materials to meet the requirements of advanced aero-engines. For example, the turbine inlet temperature of existing engines with a thrust-to-weight ratio of 10 has reached 1500℃, while the average turbine inlet temperature of engines with a thrust-to-weight ratio of 12-15 will exceed 1800℃, which far exceeds the operating temperatures of high-temperature alloys and intermetallic compounds. Increasing the inlet temperature of aero-engines can achieve higher fuel efficiency and reduce nitrogen oxide emissions. Although the application of thermal barrier coatings on nickel-based alloys has continuously increased the temperature of the front-end inlet of aero-engines, improving their efficiency, it has reached the service limit of the alloy and is difficult to meet the higher service temperatures of the future. Currently, the nickel-based high-temperature alloy material with the best heat resistance can only operate at around 1100℃. In service environments with temperatures of 1200℃ and above, improving the high-temperature performance of hot-end components is the current direction of materials research. Therefore, ceramic matrix composites, due to their excellent high temperature resistance and corrosion resistance, will drive the development of aero engines towards higher efficiency and higher thrust-to-weight ratio, and are the only choice for further improving the performance of future aero engines.

[0003] SiC fiber reinforced SiC ceramics (SiC f SiC composite materials can withstand operating temperatures up to 1650℃, making them considered ideal materials for hot-section structural components in aero-engines. Therefore, SiC... f SiC composites have become a candidate material for hot-section components of next-generation aero-engines due to their excellent high-temperature resistance. However, high-temperature components of aero-engines face challenges such as foreign object damage, water-oxygen and calcium-magnesium-aluminum-silicate corrosion (CMAS) during service, limiting their practical application. Thermal barrier coatings can mitigate the high-temperature mechanical property degradation and high-temperature corrosion failure of ceramic matrix composites, providing a solution for SiC... f / SiC composite materials offer the possibility of being applied in practice.

[0004] Rare earth monosilicate ceramics (RE2SiO5) exhibit good phase stability, low thermal conductivity, and excellent resistance to water vapor corrosion and CMAS corrosion under high-temperature conditions, making them one of the internationally recognized thermal barrier coatings. However, at 1200℃, the coefficient of thermal expansion of X1-RE2SiO5 (RE = La, Nd, Sm, Eu, and Gd) ranges from (8.3-9.2) × 10⁻⁶. −6 K−1 Between these ranges, the coefficient of thermal expansion of X2-RE2SiO5 (RE = Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) is between (6.94-8.84) × 10⁻⁶. −6 K −1 Between room temperature and 1200℃, both are related to SiC f The coefficient of thermal expansion of the SiC composite matrix is ​​(4.5-5.5) × 10⁻⁶. −6 K −1 The coefficient of thermal expansion of the coating material differs significantly from that of SiC, making it prone to cracking and stress mismatch under high-temperature conditions, leading to coating material peeling. Therefore, the coefficient of thermal expansion of the coating material is significantly different from that of SiC. f The mismatch in the coefficient of thermal expansion of SiC composite materials is the main factor limiting their application and a bottleneck.

[0005] When used as a thermal barrier coating material, single rare-earth silicate ceramics may not simultaneously meet all conditions, making it difficult to achieve resistance to CMAS corrosion at high temperatures. The novel concept of high-entropy design provides a new approach for the development of high-entropy rare-earth silicate ceramics, allowing for the control of their performance by regulating their composition and structure. High-entropy design can regulate the composition, size, and chemical bond complexity of metal cation positions within the crystal structure, achieving synergistic effects among multiple components, improving the stability of the crystal structure, and providing new scientific insights for materials design.

[0006] Currently, there are few reports on the synthesis methods of porous high-entropy rare-earth monosilicate ceramics, mainly solid-state reaction methods. Solid-state reaction methods (e.g., W. Liao, Y. Tan, C. Zhu, Z. Teng, P. Jia, H. Zhang, Synthesis, microstructures, and corrosion behaviors of multi-components rare-earthsilicates, Ceramics International 47(23) (2021) 32641-32647) have advantages such as low cost, high yield, and simple preparation process, and are currently the most commonly used method for synthesizing high-entropy rare-earth monosilicate ceramic powders. However, this method has problems such as high synthesis temperature (≥1600℃), uneven element distribution, impurity phases, and small composition synthesis space, which seriously limit the development and application of high-performance porous high-entropy rare-earth monosilicate ceramics.

[0007] Therefore, it is of great significance to develop a porous high-entropy rare earth monosilicate ceramic powder preparation technology with low synthesis temperature, simple equipment, and simple and controllable process, and to prepare porous high-entropy rare earth monosilicate ceramic powder with uniform element distribution, high purity, large component space, and low thermal conductivity. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a porous high-entropy rare earth monosilicate ceramic powder, its preparation method, and its application.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for preparing porous high-entropy rare-earth monosilicate ceramic powder includes the following steps:

[0011] S1. Dissolve tetraethyl orthosilicate in anhydrous ethanol and stir thoroughly to obtain a silicon source solution;

[0012] S2. Add the silicon source solution to the rare earth nitrate solution and stir thoroughly to obtain a mixed solution;

[0013] S3. Add sodium hydroxide solution to the mixed solution as a rare earth ion coprecipitant and tetraethyl orthosilicate condensation catalyst, place it in a reactor and seal it for 24-60 h, then separate and dry to obtain the precursor gel.

[0014] S4. The precursor gel is calcined at 1350-1400℃ for 2-4 hours and then quenched to room temperature to obtain porous high-entropy rare earth monosilicate ceramic powder.

[0015] The SiO2 content in the above tetraethyl orthosilicate is ≥28%.

[0016] The above-mentioned rare earth nitrate solution includes, but is not limited to, at least four rare earth nitrates selected from Ho(NO3)3•5H2O, Lu(NO3)3•6H2O, Yb(NO3)3•5H2O, Eu(NO3)3•6H2O, and Dy(NO3)3•6H2O dissolved in deionized water, wherein the purity of the rare earth nitrates is ≥99.99%.

[0017] The ratio of the total molar amount of rare earth element atoms in the rare earth nitrate solution described in S2 to the molar amount of Si atoms in tetraethyl orthosilicate is 1:0.4-0.6.

[0018] The concentration of the sodium hydroxide solution mentioned above is 1.2-3.0 mol / L.

[0019] The inner liner of the aforementioned reactor contains polytetrafluoroethylene.

[0020] In S3, a heat-insulating and sealed reaction is carried out. The heat-insulating temperature is 60-100℃, and the reaction is separated and dried after cooling to room temperature.

[0021] The heating rate in S4 is 6-12℃ / min.

[0022] The second aspect of the present invention provides a porous high-entropy rare earth monosilicate ceramic powder, which is obtained by the above preparation method, and the average pore size of the porous high-entropy rare earth monosilicate ceramic powder is 100-800 nm.

[0023] The third aspect of this invention provides the application of the above-mentioned porous high-entropy rare earth monosilicate ceramic powder in aero engines, specifically its application in the thermal barrier coating of aero engines.

[0024] The beneficial effects of this invention are:

[0025] This invention uses tetraethyl orthosilicate as an organosilicon source. Under the catalysis of sodium hydroxide, a condensation reaction occurs to form SiO2 with a spatial network structure. This SiO2 reacts with co-precipitated rare earth hydroxides to form a precursor with a gel structure, which is beneficial for obtaining high-entropy rare earth monosilicate products with porous structures during subsequent calcination.

[0026] The porous high-entropy rare earth monosilicate ceramic powder preparation technology of the present invention can achieve uniform mixing of rare earth nitrate solution, tetraethyl orthosilicate-ethanol solution and sodium hydroxide solution, realizing atomic-level mixing and reaction of raw materials; in the precursor gel synthesis process, heating can not only improve solubility, but also reduce solvent consumption, especially in large-scale production applications, which can significantly reduce the demand for solvents.

[0027] This invention can synthesize porous high-entropy rare earth monosilicate ceramic powder with an X2-RE2SiO5 structure by adjusting the composition space. It has excellent properties such as uniform element distribution, large composition space, no impurity phase, and low thermal conductivity, as well as advantages such as low synthesis temperature, simple equipment, and controllable process. It is suitable for use in hot-end components of aero-engines and has broad application prospects. Attached Figure Description

[0028] Figure 1 The XRD patterns of porous high-entropy rare-earth monosilicate ceramic powders from Examples 1-2 are shown below.

[0029] Figure 2 The image shows the SEM and EDS elemental distribution of the porous high-entropy rare-earth monosilicate ceramic powder in Example 1.

[0030] Figure 3 The image shows the SEM and EDS elemental distribution of the porous high-entropy rare-earth monosilicate ceramic powder in Example 2.

[0031] Figure 4 The XRD patterns of the porous high-entropy rare-earth monosilicate ceramic powders from Examples 3-4 are shown.

[0032] Figure 5 The XRD patterns of the porous high-entropy rare-earth monosilicate ceramic powders in Comparative Examples 1-2 are shown below.

[0033] Figure 6 The XRD patterns of the porous high-entropy rare earth monosilicate ceramic powders in Comparative Examples 3-4 are shown. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The purity of rare earth nitrates Ho(NO3)3•5H2O, Yb(NO3)3•5H2O, Lu(NO3)3•6H2O, Eu(NO3)3•6H2O, and Dy(NO3)3•6H2O in Examples 1-4 and Comparative Examples 1-4 is ≥99.99%.

[0036] In Examples 1-4 and Comparative Examples 1-4, the tetraethyl orthosilicate ((C2H5O)4Si, TEOS) contained ≥28% SiO2.

[0037] Example 1

[0038] A porous, high-entropy rare-earth monosilicate ceramic powder is prepared by the following method:

[0039] S1. Weigh 0.3528g Ho(NO3)3•5H2O, 0.3593g Yb(NO3)3•5H2O, 0.3573g Lu(NO3)3•6H2O, and 0.3568g Eu(NO3)3•6H2O, add deionized water to a final volume of 40mL to obtain a rare earth nitrate solution with each rare earth cation at 0.02mol / L. Then add a silicon source solution containing 0.3573mL tetraethyl orthosilicate and 10mL ethanol, stir magnetically for 10min, and immediately add 10mL of 1.2mol / L NaOH solution, continuing to stir magnetically for 30min.

[0040] S2. Transfer the solution obtained in step S1 to a hydrothermal reactor with a polytetrafluoroethylene liner, seal it, and place it in an 80°C oven for 48 hours. After cooling, centrifuge and wash with water three times, then dry the obtained gel-like substance in a 100°C oven to obtain the precursor gel.

[0041] S3. Place the precursor gel in a muffle furnace, first control the heating rate to rise from room temperature to 1400℃ at 10℃ / min, then hold for 2 hours, and then quench in air to room temperature to obtain porous high-entropy rare earth monosilicate ceramic powder. (Ho) 0.25 Yb 0.25 Lu 0.25 Eu 0.25 )2SiO5, labeled as S-1c1v.

[0042] Performance testing:

[0043] The porous high-entropy rare-earth monosilicate ceramic powder (Ho) in this embodiment 0.25 Yb 0.25 Lu 0.25 Eu 0.25 The X-ray diffraction (XRD) pattern of 2SiO5 is shown below. Figure 1 As shown, the scanning electron microscope (SEM) image and energy-dispersive X-ray spectroscopy (EDS) elemental distribution map are as follows: Figure 2 As shown.

[0044] Depend on Figure 1 It can be seen that the porous high-entropy rare earth monosilicate ceramic powder in this embodiment has a single X2-RE2SiO5 structure and no other impurity phases were found.

[0045] Depend on Figure 2 It can be seen that the high-entropy rare earth monosilicate ceramic powder in this embodiment has a porous structure, with uniform distribution of metal elements and no obvious segregation.

[0046] Example 2:

[0047] A porous, high-entropy rare-earth monosilicate ceramic powder is prepared by the following method:

[0048] S1. Weigh 0.3528g Ho(NO3)3•5H2O, 0.3593g Yb(NO3)3•5H2O, 0.3573g Lu(NO3)3•6H2O, 0.3568g Eu(NO3)3•6H2O, and 0.3653g Dy(NO3)3•6H2O, then add deionized water to a final volume of 40mL to obtain a rare earth nitrate solution with each rare earth cation at 0.02mol / L. Then add a silicon source solution containing 0.4468mL tetraethyl orthosilicate and 10mL ethanol, and stir magnetically for 10min. Immediately afterwards, add 10mL of 1.2mol / L NaOH solution and continue stirring magnetically for 30min.

[0049] S2. Transfer the mixed solution obtained in step S1 to a hydrothermal reactor with a polytetrafluoroethylene liner, seal it, and place it in an 80°C oven for 48 hours. After cooling, centrifuge and wash with water three times, then dry the obtained gel-like substance in a 100°C oven to obtain the precursor gel.

[0050] S3. Place the precursor gel in a muffle furnace, first control the heating rate to rise from room temperature to 1400℃ at 10℃ / min, then hold for 2 hours, and then quench in air to room temperature to obtain porous high-entropy rare earth monosilicate ceramic powder. (Ho) 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Dy 0.2 )2SiO5.

[0051] Performance testing:

[0052] The porous high-entropy rare-earth monosilicate ceramic powder (Ho) in this embodiment 0.2 Yb 0.2 Lu 0.2 Eu 0.2 Dy 0.2 The XRD pattern of 2SiO5 is shown below. Figure 1 As shown, the SEM image and EDS element distribution map are as follows: Figure 3 As shown.

[0053] Depend on Figure 1 It can be seen that the porous high-entropy rare earth monosilicate ceramic powder in this embodiment has a single X2-RE2SiO5 structure and no other impurity phases were found.

[0054] Depend on Figure 3 It can be seen that the high-entropy rare earth monosilicate ceramic powder in this embodiment has a porous structure, with uniform distribution of metal elements and no obvious segregation.

[0055] Example 3:

[0056] A porous, high-entropy rare-earth monosilicate ceramic powder is prepared by the following method:

[0057] S1. Weigh 0.7036g Ho(NO3)3•5H2O, 0.7186g Yb(NO3)3•5H2O, 0.7506g Lu(NO3)3•6H2O, and 0.7136g Eu(NO3)3•6H2O, dissolve them in deionized water, and bring the volume to 40mL to obtain a rare earth nitrate solution with each rare earth cation at 0.04mol / L. Then add a silicon source solution containing 0.7146mL tetraethyl orthosilicate and 10mL ethanol, and stir magnetically for 10min. Immediately afterwards, add 10mL of 2.4mol / L NaOH solution and continue stirring magnetically for 30min.

[0058] S2. Transfer the solution obtained in step S1 to a hydrothermal reactor with a polytetrafluoroethylene liner, seal it, and place it in a 100°C oven for 24 hours. After cooling, centrifuge and wash with water three times, then dry the obtained gel-like substance in a 100°C oven to obtain the precursor gel.

[0059] S3. Place the precursor gel in a muffle furnace, first control the heating rate to rise from room temperature to 1380℃ at 12℃ / min, then hold for 4 hours, and then quench in air to room temperature to obtain porous high-entropy rare earth monosilicate ceramic powder. (Ho) 0.25 Yb 0.25 Lu 0.25 Eu 0.25 )2SiO5, labeled as S-2c1v.

[0060] Performance testing:

[0061] The high-entropy rare-earth monosilicate ceramic powder (Ho) in this embodiment 0.25 Yb 0.25 Lu 0.25 Eu 0.25 The XRD pattern of 2SiO5 is shown below. Figure 4 As shown.

[0062] Depend on Figure 4 It can be seen that the high-entropy rare earth monosilicate ceramic powder in this embodiment has a single X2-RE2SiO5 structure and no other impurity phases were found.

[0063] Example 4:

[0064] A porous, high-entropy rare-earth monosilicate ceramic powder is prepared by the following method:

[0065] S1. Weigh 2.117g Ho(NO3)3•5H2O, 2.156g Yb(NO3)3•5H2O, 2.252g Lu(NO3)3•6H2O, and 2.141g Eu(NO3)3•6H2O, dissolve them in deionized water, and bring the volume to 120mL to obtain a rare earth nitrate solution with each rare earth cation at 0.04mol / L. Then add a silicon source solution containing 2.1438mL tetraethyl orthosilicate and 30mL ethanol, and stir magnetically for 10min. Immediately afterward, add 30mL of 3mol / L NaOH solution and continue stirring magnetically for 30min.

[0066] S2. Transfer the solution obtained in step S1 to a hydrothermal reactor with a polytetrafluoroethylene liner, seal it, and place it in a 60°C oven for 60 hours. After cooling, centrifuge and wash with water three times, then dry the obtained gel-like substance in a 100°C oven to obtain the precursor gel.

[0067] S3. Place the precursor gel in a muffle furnace, first control the heating rate to rise from room temperature to 1350℃ at 6℃ / min, then hold for 3 hours, and then quench in air to room temperature to obtain porous high-entropy rare earth monosilicate ceramic powder. (Ho) 0.25 Yb 0.25 Lu 0.25 Eu 0.25 )2SiO5, labeled as S-2c3v.

[0068] Performance testing:

[0069] The high-entropy rare-earth monosilicate ceramic powder (Ho) in this embodiment 0.25 Yb 0.25 Lu 0.25 Eu 0.25 The XRD pattern of 2SiO5 is shown below. Figure 4 As shown.

[0070] Depend on Figure 4 It can be seen that the high-entropy rare earth monosilicate ceramic powder in this embodiment has a single X2-RE2SiO5 structure and no other impurity phases were found.

[0071] Comparative Example 1:

[0072] A high-entropy rare-earth silicate ceramic powder is prepared in the same way as in Example 1, except that the "10 mL 1.2 mol / L sodium hydroxide solution" in S1 is changed to "no sodium hydroxide solution is added" during preparation (the high-entropy rare-earth silicate ceramic powder prepared is referred to as S-1).

[0073] Performance testing:

[0074] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (S-1) in this comparative example is shown below. Figure 5 As shown.

[0075] Depend on Figure 5 It can be seen that when sodium hydroxide solution is not added as a catalyst and co-precipitant, the prepared powder is mainly a high-entropy rare-earth disilicate phase, containing a very small amount of high-entropy rare-earth monosilicate phase. This is because the reaction Gibbs free energy of disilicates is relatively low, making it easier to form the disilicate phase. The addition of sodium hydroxide solution can inhibit the formation of the disilicate phase. However, without the addition of sodium hydroxide solution, the yield of the high-entropy rare-earth disilicate phase is low.

[0076] Comparative Example 2

[0077] A high-entropy rare-earth monosilicate ceramic powder is prepared in the same manner as in Example 1, except that the "10 mL 1.2 mol / L sodium hydroxide solution" in S1 is changed to "10 mL 2.4 mol / L sodium hydroxide solution". (The high-entropy rare-earth silicate ceramic powder prepared is referred to as S-2).

[0078] The XRD pattern of the high-entropy rare-earth monosilicate ceramic powder (S-2) in this comparative example is shown below. Figure 5 As shown.

[0079] Depend on Figure 5 It can be seen that when the concentration of sodium hydroxide solution is increased by 1 time, porous high-entropy rare earth monosilicate ceramic powder is prepared, with high product purity and increased yield.

[0080] Comparative Example 3

[0081] A high-entropy rare-earth silicate ceramic powder is prepared in exactly the same way as in Example 1, except that the calcination temperature in S3 is adjusted from "1400℃" to "1200℃" (the high-entropy rare-earth silicate ceramic powder prepared is denoted as S-3).

[0082] Performance testing:

[0083] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (S-3) in this comparative example is shown below. Figure 6 As shown.

[0084] Depend on Figure 6 It can be seen that when the calcination temperature is 1200℃, the powder obtained is mainly X1-RE2SiO5 phase, indicating that the calcination temperature is insufficient to provide enough energy for the formation of X2-RE2SiO5. Increasing the temperature can transform the X1 phase into the X2 phase.

[0085] Comparative Example 4

[0086] A high-entropy rare-earth silicate ceramic powder is prepared exactly the same as in Example 1, except that the calcination temperature in S3 is adjusted from "1400℃" to "1300℃" (the high-entropy rare-earth silicate ceramic powder prepared is designated as S-4).

[0087] Performance testing:

[0088] The XRD pattern of the high-entropy rare-earth silicate ceramic powder (S-4) in this comparative example is shown below. Figure 6 As shown.

[0089] Depend on Figure 6It can be seen that when the calcination temperature is 1300℃, the powder obtained is mainly X2-RE2SiO5 phase, indicating that the calcination temperature provides sufficient energy for the formation of X2-RE2SiO5. Increasing the temperature can transform the X1 phase into the X2 phase, but the temperature is not high enough, and there are still a very small amount of impurity phases.

[0090] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing porous high-entropy rare-earth monosilicate ceramic powder, characterized in that, Includes the following steps: S1. Dissolve tetraethyl orthosilicate in anhydrous ethanol and stir thoroughly to obtain a silicon source solution; S2. Add the silicon source solution to the rare earth nitrate solution and stir thoroughly to obtain a mixed solution. The rare earth nitrate solution comprises at least four rare earth nitrates selected from Ho(NO3)3•5H2O, Lu(NO3)3•6H2O, Yb(NO3)3•5H2O, Eu(NO3)3•6H2O, and Dy(NO3)3•6H2O dissolved in deionized water. S3. Add sodium hydroxide solution to the mixed solution as a rare earth ion coprecipitant and tetraethyl orthosilicate condensation catalyst, place it in a reactor and seal it for 24-60 h, then separate and dry to obtain the precursor gel. S4. The precursor gel is calcined at 1350-1400℃ for 2-4 hours and then quenched to room temperature to obtain porous high-entropy rare earth monosilicate ceramic powder.

2. The preparation method according to claim 1, characterized in that: The tetraethyl orthosilicate contains ≥28% SiO2.

3. The preparation method according to claim 1, characterized in that: The purity of the rare earth nitrate is ≥99.99%.

4. The preparation method according to claim 1, characterized in that: The ratio of the total molar amount of rare earth element atoms in the rare earth nitrate solution described in S2 to the molar amount of Si atoms in tetraethyl orthosilicate is 1:0.4-0.

6.

5. The preparation method according to claim 1, characterized in that: The concentration of the sodium hydroxide solution is 1.2-3.0 mol / L.

6. The preparation method according to claim 1, characterized in that: The reactor liner contains polytetrafluoroethylene.

7. The preparation method according to claim 1, characterized in that: In S3, a heat-insulating and sealed reaction is carried out. The heat-insulating temperature is 60-100℃, and the reaction is separated and dried after cooling to room temperature.

8. The preparation method according to claim 1, characterized in that: The heating rate in S4 is 6-12℃ / min.

9. A porous, high-entropy rare-earth monosilicate ceramic powder, characterized in that: The porous high-entropy rare earth monosilicate ceramic powder obtained by any one of the preparation methods in claims 1-8 has an average pore size of 100-800 nm.

10. The application of the porous high-entropy rare earth monosilicate ceramic powder according to claim 9 in aero-engines.

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